The present invention relates to a titanium-containing solid catalyst useful for production of epoxy compounds and a process for producing epoxy compounds by using the catalyst.
As a process for producing an epoxy compound by reacting an olefin compound with a peroxide in the presence of a titanium-containing solid catalyst, several processes are conventionally known, for example, those described in JP-B-50-30049, JP-B-54-40525, JP-B-54-40526, JP-B-56-35491 and JP-A-8-269031.
The above-described titanium-containing solid catalyst can be prepared in various processes. Among them, useful is a process of calcining the titanium compound which has been impregnated into a silica gel carrier in a solvent. As the titanium compound, titanium saturated alkoxides are employed most frequently. Conversion of a titanium alkoxide into titanium oxide when it is supported on a carrier, however, prevents the solid catalyst thus prepared from exhibiting catalytic activity in an epoxidation reaction.
In general, use of highly dispersed titanium having a tetrahedral structure is necessary for production of a titanium-containing solid catalyst capable of exhibiting a high activity in an epoxidation reaction. For producing such catalyst containing highly dispersed titanium, a stable titanium alkoxide must be prepared by suppressing generation of clusters of titanium oxide or titanium during preparation of the catalyst.
For preparing the above-described catalyst, use of a bulky saturated alcohol, for example, cyclohexanol (Chem. Commun. 2000, 855) is generally known. To achieve a higher activity in an epoxidation reaction, preparation of more stable titanium alkoxide is required.
An object of the present invention is to provide a titanium-containing solid catalyst having a high activity and a high epoxy selectivity by overcoming the above-described problems involved in the titanium alkoxide preparation for improving the activity of the catalyst in the production of an epoxy compound (oxysilane compound), and also to provide a process for producing epoxy compounds using this catalyst.
In order to attaining the above-described object, the present inventors have carried out an extensive investigation. As a result, it has been found that when an alkynyl alcohol is used for preparation of a titanium alkoxide from a titanium compound raw material, a titanium alkynyl alkoxide can be prepared readily; that the titanium alkynyl alkoxide supported on silica gel is stable; and that a catalyst obtainable by calcining a titanium alkynyl alkoxide supported on a silica gel has a high activity and a high epoxy selectivity, to complete the invention.
In the present invention, there is thus provided a titanium-containing solid catalyst obtainable by calcining a titanium alkynyl alkoxide supported on a silica gel.
In the present invention, there is also provided a process for producing an epoxy compound, which comprises reacting an olefin compound with a peroxide in the presence of the above-described titanium-containing solid catalyst.